this top, but it couldn't track it back to a pattern. I did find instructions for the stitch on MyPicot crochet site, here. I experimented crocheting the stitch with three different size hooks. I think the biggest one, 6 mm, is too loose and floppity. The smallest one, 4 mm, is not bad, but a bit stiff. The goldilocks one is 4.5 mm, in the middle of my sample.
So I have the stitch, but not a pattern. I'm using my favourite knitted top as a template: